Context: Indian Council of Medical Research (ICMR) has announced that 51 private laboratories [accredited by the National Accreditation Board for Testing and Calibration Laboratories (NABL)] will soon be allowed to test for COVID-19 to enhance capacity for diagnosis and detection in addition to the 72 functional laboratories.
- The announcement has come amid the “test, test, test” prescription of the World Health Organisation (WHO).
- According to the ICMR, the “test, test, test” prescription is not for India as community transmission of COVID-19 has not yet occurred.
Spread of COVID-19 in India
- India has witnessed only imported cases of COVID-19 and limited local transmission from imported cases to their immediate contacts.
- Community transmission of the disease has not been documented till now.
- If community transmission is documented, the testing strategy of India needs to undergo changes to evolve into a stage appropriate testing strategy.
Current testing apparatus:
- 72 functional ICMR laboratories in government sector for testing
- 49 more under organisations like Council of Scientific & Industrial Research (CSIR), Department of Biotechnology (DBT), and Defence Research, Development Organisation (DRDO) will be active by the month end.
- Private NABL accredited laboratories will soon be operationalised.
New guidelines for scaling up testing:
- ICMR has also scaled up its testing operations and has released revised testing guidelines which includes testing norms for health care workers looking after patients with respiratory distress.
- Health care workers managing respiratory distress / Severe Acute Respiratory Illness should be tested when they are symptomatic.
- The revised norms specify that all asymptomatic patients, who have taken international flights in the past 14 days, should get tested as per current protocol if they develop symptoms.
- Also symptomatic people who come in close contact with laboratory-confirmed coronavirus cases must be tested.
- Appealing all private laboratories to offer COVID-19 diagnosis free of cost. Also, the Union Health Ministry has made it mandatory for private institutions to notify coronavirus (COVID-19) patients.
- Guidelines to labs
- The Council also issued guidelines to private sector labs stating that the test should be only offered when prescribed by a qualified physician as per the ICMR guidance for testing.
- Appropriate biosafety and biosecurity precautions should be ensured while collecting samples from a suspect patient.
- Alternatively, a disease-specific separate collection site may be created.
- Also, all the private testing laboratories are to ensure immediate/real-time reporting to State officials of the Integrated Disease Surveillance Programme and ICMR headquarters for timely initiation of contact tracing and research activities.
7. Handling of bodies
- The Health Ministry issued an advisory on handling of bodies with COVID-19 stating that autopsies should be avoided.
- If autopsy is to be performed for special reasons, a well-trained and limited staff should be used.
Five steps to detecting the coronavirus (COVID-19)
Collection and transport
- Testing centre takes swabs from nasal cavities and back of the throat (pharynx), and puts samples in a virus transport medium, which contains balanced salts and albumin to prevent the virus from disintegrating.
- Sample is then transported in cold storage to the testing lab.
Extraction of viral RNA
- The current SARS-CoV-2 which has caused the COVID-19 pandemic, have large single-stranded RNA genomes.
- Testing lab extracts the RNA from the samples, using commercially available kits (such as those made by companies like QIAGEN.)
Putting THE RNA in THE PCR mix
- Extracted RNA is added to a polymerase chain reaction (PCR) mix.
- This includes the master mix, which contains a reverse transcriptase enzyme that converts the RNA into DNA.
- Finally, the PCR mix consists of a “housekeeping” gene - a normal human gene (RNase P) that is used to ensure that samples were properly collected, and RNA extracted.
AmpLification of the viral DNA
Samples are then put in a thermal cycler machine that is used to conduct the PCR process.
First, the RNA is converted into DNA. Then the process of copying the genes starts.
Testing against controls
Amplified DNA is tested against a positive control, which usually consists of genes of the virus cloned into plasmid, and a negative control, which is a known sample that has tested negative for the virus earlier.